There are several good reasons to get rid of public folders in Exchange 2010. The one that prominently stands out is the replication model. When it comes to reliable replication and failover in Exchange 2010, mailbox databases benefit from database availability groups(DAGs). However, public folder database replication didn’t improve much, and troubleshooting public folder replication as a whole proved exceedingly difficult.
Enter Exchange 2013 modern public folders
Due to popular demand, public folders remain in Exchange Server 2013 and have been re-imagined. Even though Microsoft encouraged organizations to move away from public folders for years, end users still find them valuable. Additionally, companies that rely on large public folder hierarchies find it difficult to migrate away from them.